Control arrangement for unwinding equipment for webs

Abstract

A control arrangement for controlling web unwinding equipment used for feeding webs to a web-fed rotary printing machine stabilizes a swing roll used to tension the web at a central position via an integrator in a manner independent of the coefficient of friction. A proportional and differential element is connected in parallel with the integrator. The inputs of the integrator and the proportional and differential element are connected directly or indirectly to a swing-roll transmitter whose output is dependent on a position of the swing roll. The outputs of the integrator and the proportional and differential element act on an adder element. The output of the adder element acts directly or indirectly on a brake for braking the rotation of the wound roll.

We claim:  
     
       1. A control arrangement for controlling web unwinding equipment used for unwinding a web from a wound roll for feeding a web-fed rotary printing machine, said web unwinding equipment including a swing roller arranged in a loop of the web for keeping a constant tension on the web, wherein the swing roller is movable to maintain the constant tension, said control arrangement comprising: 
       a transmitter having a transmitter output and operatively connectable for monitoring a position of the swing roller, said output being dependent on the position of the swing roller;  
       an integrator having an input connected to said transmitter output and having an integrator output;  
       a proportional and differential element having an input connected to said transmitter output and having a proportional and differential output;  
       a first adder having inputs connected to said integrator output and said proportional+differential output and having a first adder output; and  
       a braking element operatively connectable to the wound roll for generating a braking force for braking said wound roll, wherein a value of said braking force is responsive to said adder output.  
     
     
       2. The control arrangement of  claim 1 , further comprising a characteristic-curve generator having an input connected to the transmitter output and having a characteristic-curve output connected to said integrator input and said proportional and differential element input, such that said integrator and said proportional and differential element are connected to said transmission output via said characteristic curve generator. 
     
     
       3. The control arrangement of  claim 1 , wherein said integrator is connected to a starting value input signal and wherein said first adder element is connected to a minimum pressure value (p) input signal. 
     
     
       4. The control arrangement of  claim 1 , further comprising: 
       a multiplier element having an input connected to said proportional and differential element output and having a multiplier output connected as an input to said first adder element; and  
       a second adder element having inputs connected to said integrator output and to a minimum gain (v) input signal and an output connected to said multiplier element.  
     
     
       5. A control arrangement for controlling web unwinding equipment used for unwinding a web from a wound roll for feeding a web-fed rotary printing machine, comprising: 
       a swing roller operatively arranged in a loop of the web for keeping a constant tension on the web, wherein the swing roller is movable from a central position to maintain the constant tension;  
       a transmitter having a transmitter output and operatively connectable for monitoring a position of said swing roller, said output being dependent on the position of said swing roller;  
       a two-quadrant drive operatively connectable to the wound roll for applying a torque to a core of the wound roll, thereby exerting an influence on the rotational speed of the wound roll;  
       a motor controller for controlling said two-quadrant drive, said motor controller being connected to a synchronous rotation speed input signal comprising a rotational speed of the web divided by the diameter of a replacement wound roll;  
       an integrator having an input connected to said transmitter output and having an integrator output;  
       a first polarity-dependent element having an input arranged for receiving said transmitter output and having a first polarity-dependent output;  
       a proportional and differential element having an input connected to said first polarity-dependent output and having a proportional and differential output;  
       a second polarity-dependent element having an input arranged for receiving said transmitter output and having a second polarity-dependent output connected to said motor controller;  
       a first adder having inputs connected to said integrator output and said proportional and differential output and having a first adder output;  
       a braking element operatively connectable to the wound roll for generating a braking force for braking the rotation of the round wound roll; and  
       an electro-pneumatic converter having an input connected to said adder output and an electro-pneumatic converter output connected to said braking element, wherein a value of said braking force is responsive to said electro-pneumatic converter output.  
     
     
       6. The control arrangement of  claim 5 , further comprising a characteristic-curve generator having an input connected to the transmitter output and having a characteristic-curve output connected to said integrator input, said first polarity-dependent element input, and said second polarity-dependent element input such that each of said integrator, said first polarity-dependent element, and said second polarity-dependent element are connected to said transmission output via said characteristic curve generator. 
     
     
       7. The control arrangement of  claim 5 , wherein said integrator further comprises a connection to a starting value input signal and wherein said first adder element further comprises a connection to a minimum pressure value (p) input signal. 
     
     
       8. The control arrangement of  claim 5 , further comprising: 
       a first multiplier element having an input connected to said proportional and differential element output and having a first multiplier output connected as an input to said first adder element; and  
       a second adder element having inputs connected to said integrator output and a minimum gain (v) input signal and an output connected to said multiplier element.  
     
     
       9. The control arrangement of  claim 8 , further comprising: 
       an inverter connected between said second polarity-dependent element and said motor controller; and  
       a second multiplier element having inputs connected to the inverter output and said second adder element output and having a second multiplier element output connected to said motor controller.  
     
     
       10. The control arrangement of  claim 5 , wherein at least a portion of said control arrangement is implemented via a computer.